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  1. Rleo6965

    Velleman K8055 blowing up ULN2803

    I can't find ULN2803 on the diagram.:confused:
  2. Rleo6965

    Problems building first circuit - capacitor ESR meter

    @Jaynuts I'm just wondering of D2 connection in your provided diagram. It seems dc voltage after D1 will pass directly on forward bias D2 to ground. What would be left voltage to be measured by your uA meter?
  3. Rleo6965

    Velleman K8055 blowing up ULN2803

    It seems everything was working. How about post the circuit diagram. We might find something.:)
  4. Rleo6965

    Problems building first circuit - capacitor ESR meter

    @jaynuts What kind of diode you use in D1 and D2?
  5. Rleo6965

    Velleman K8055 blowing up ULN2803

    Can you try connecting Relay pin 86 to +24V and pin85 in series with an ammeter then connect to ground. Let's see if relay will activate or draw normal current of 70ma.
  6. Rleo6965

    Velleman K8055 blowing up ULN2803

    Relay have built-in diode. Is it possible that Relay coil w/ diode was connect in reverse. That is, +24V supply pass thru relay built-in diode ( forward bias ) and destroy output of ULN2803. When relay driver ic was turned on and sink its output. Thus output draw high current trying to sink +24V...
  7. Rleo6965

    Want to build ESR Tester

    . Thanks for the info. I want to build ESR Tester. So, I'm looking for good working schematic of ESR. There so many schematic of ESR. But I don't know which one was better. I saw one with ferrite transformer. How about this one?. No ferrite transformer. http://kakopa.com/ESR_meter/
  8. Rleo6965

    Want to build ESR Tester

    I have 40 yrs in experience with electronics ( from Data General Minicomputer to now Micros POS ) but never tried use or build an ESR Tester. I thought its not useful tool for electronics.:D Can you guys recommend good working, tested ESR project? Thanks in advance.
  9. Rleo6965

    Can I use 2 x transformers?

    @Balrock This is my first time saw this kind of ps diagram. Is that half wave rectifier for each voltage regulator?
  10. Rleo6965

    Can I use 2 x transformers?

    I think you can. You have to use 2 bridge diode for each transformer. Bridge1 for +24V and -side of rectifier would be connected to ground. Bridge2 for -24V and +side of rectifier would be connected to ground.
  11. Rleo6965

    Checking a capacitor

    What kind of tester have you bought?
  12. Rleo6965

    DIY PCB

    Yes. It's very cheap a bottle. Use the remaining varnish to your old wooden furniture to make it look new.:D
  13. Rleo6965

    DIY PCB

    How about you try to apply plastic varnish on that portion and apply solder then test for continuity. Then you will now what I'm explaining. To see is to believe.
  14. Rleo6965

    4017 Decade counter

    Oh you want detailed or step by step explanation. Let's wait for other members to post. They have better english and knowledge than me.:)
  15. Rleo6965

    4017 Decade counter

    This was already answered by duke37. Think and use your imagination. What will happen if you replaced 4 diodes with jumper wire.? You will be shorting Q5,Q6,Q7,Q8 and damage the 4017 ic.
  16. Rleo6965

    4017 Decade counter

    Same here.:D Vick post your diagram. I hope we won't be discussing internal circuit of IC.:D
  17. Rleo6965

    Need help with strobe circuit

    This was your diagram that you posted. I mark with red line for correct connection.
  18. Rleo6965

    DIY PCB

    If you mean the copper etch. Yes, it will be insulated by varnish coating. But you can still solder on it. You can still place your multimeter probe to test voltage , resistance or continuity of copper. Just add little pressure to the probe to puncture varnish coating. You have to apply thin...
  19. Rleo6965

    Need help with strobe circuit

    Timer2 Pin8 should not be connected to pin3 of Timer1. Timer2 pin8 must be connected to +5V. Connect 0.1 mfd to pin or CV of 2 timer to ground.
  20. Rleo6965

    DIY PCB

    Yes. You can still solder on on pcb connection. Hot solder lead will melt plastic varnish and solder flow on etch copper..
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